PROJECT SUMMARY/ABSTRACT We propose to examine trends in couples? work and earnings in the years following childbirth and the implications of these couple-level processes for changes in aggregate inequality over time. We will address critical gaps in the literature regarding how couples sort into marriage and how they negotiate roles within marriage. Consistent with a shift away from sex-differentiated specialization in marriage, socioeconomic characteristics predicting marriage have grown more similar for men and women over time, as have the earnings of husbands and wives within marriage. Yet once married, and particularly after the birth of a child, wives take on greater domestic responsibilities and husbands take on a greater share of market work; these adjustments result in widening earnings differentials between spouses. There has been very little work on how couple-level adjustments have changed over time, how they differ for couples with high and low earnings, or what their implications might be for (a) trends in the economic resemblance of spouses or (b) trends in social inequality more broadly. Understanding the processes that generate inequality is critical given its strong links to poorer health and well-being. We will use four decades of successive, short-run panels from the Current Population Survey (CPS) to assess changes in husbands? and wives? work and earnings following a first birth. We rely on newly available identifiers from 1976-2015 to link couples longitudinally across the full 16 months of their CPS participation, resulting in 480 overlapping panels for hundreds of thousands of couples. These data are the largest and longest running longitudinal data source in the U.S. and are virtually untapped for research on family dynamics and change. We will address five specific aims: AIM 1) Develop and make syntax publicly available to produce a couple-level, longitudinal CPS database and weights from 1976-2015; AIM 2) Examine trends in the within-couple division of market work following childbirth; AIM 3) Examine how within-couple trends in the division of market work following childbirth vary by his and her prior earnings; AIM 4) Link couple- level changes in work and earnings to aggregate inequality, decomposing change in earnings inequality among couples into changes in the economic resemblance of partners before and after childbirth; AIM 5) Assess the implications of increases in divorce and nonmarital childbearing for our study results, examining trends in unmarried mothers? employment and earnings and their contributions to aggregate inequality.The research team has extensive expertise in studying U.S. family change and unparalleled experience in data integration, record linkage, and the CPS. This project offers great potential to inform science on the within-family levers that contribute to between-family divergence in economic well-being. What we learn will be directly relevant for understanding past, current, and future patterns in the health of Americans. Policy initiatives on marriage and parental leave will benefit from our findings on how parents arrange work and family demands.